The presence of one or more surfactants in a formulation may result in the formation of foam when the formulation is mixed. The formation of foam is often undesirable during manufacturing processes. This is because the foam impacts negatively on mixing processes, potentially degrading the quality of the finished product. Foams are often difficult to handle and it is generally necessary to defoam a product before it can be packed. In addition, foam increases the volume of the product meaning that large void spaces must be left in mixing vessels. Thus it can be seen that the presence of foam reduces the efficiency and reliability of manufacturing processes.
Various methods for preventing the formation of foam have been described. These include the use of chemical defoamers and the selection of mixing conditions to reduce foaming.
A list of defoaming agents suitable for use in food products is provided by the US Code of Federal Regulations Title 21, Volume 3, Part 173, Section 173.340, revised 1 Apr. 2013 (21CFR 173.340) (http://web.archive.org/web/20130914001229/http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/ctcfr/CFRSearch.cfm?FR=173.340).
EP0967965 discloses a low foaming therapeutic toothpaste containing a therapeutic substance, an abrasive, a humectant, a low foam surfactant and/or a foam control agent. Ethanol and low molecular weight polydimethylsiloxanes are identified as foam control agents. Although ethanol is effective as a defoaming agent, its storage, transportation and use are heavily regulated in many jurisdictions. These regulatory requirements make the use of ethanol expensive. The low flash point of ethanol also presents safety and handling concerns. Moreover, ethanol is not acceptable to some consumers for religious reasons. It is therefore desirable to avoid the use of ethanol. Polydimethylsiloxanes are also effective as defoaming agents but are expensive. Furthermore, many silicone oils are not orally acceptable.
There remains a need in the art for improved methods for defoaming oral care compositions.